/Engine/Plugins/Runtime/GameplayAbilities/Source/GameplayAbilities/Public/GameplayEffect.h
Attempts to populate the specified aggregator with all of the mods of the backing captured aggregator. Can fail if the spec doesn't have a valid capture yet.
True if the aggregator had mods successfully added to it, false if it did not
bool AttemptAddAggregatorModsToAggregator ( [FAggregator](API\Plugins\GameplayAbilities\FAggregator) & OutAggregatorToAddTo ) const